A population-based studyof elderly Germans, aged 75 and older, evaluated the association between alcohol consumption and incident overall dementia and Alzheimer dementia over 3 years. There was good ascertainment of the development of dementia, even among subjects who died during follow up. Of 3,202 subjects free of dementia at baseline, 217 subjects met criteria of dementia during follow up. Subjects consuming alcohol had approximately 30% less overall dementia and 40% less Alzheimer dementia than did non-drinking subjects. Unlike many previous studies showing greater effects of wine on reducing risk of dementia, no significant differences were seen according to the type of alcoholic beverage consumed. Overall, these results are similar to several previous studies in the very elderly and suggest that moderate drinking is associated with less dementia, even among individuals aged 75 years and older.

A large prospective study of men and women in northern Norway reported that moderate wine consumption was independently associated with better performance on cognitive tests after 7 years of follow up. There was no consistent association between consumption of beer or spirits and cognitive test results. The authors also reported that abstinence was associated with significantly lower cognitive performance in women. As noted by the authors, in any observational study there is the possibility of residual confounding by other lifestyle habits affecting cognitive function, and the present study was not able to adjust for certain ones (e.g., diet, income, or profession) but did adjust for age, education, body mass index, depression, and cardiovascular disease and its major risk factors.

The results of this study support findings from a number of observational, prospective studies that have shown that the moderate consumption of alcohol, especially of wine, may have favorable effects on cognitive function. Such effects could relate to the presence in wine of a number of polyphenols and other substances that reduce the risk of cognitive decline with ageing. Mechanisms that have been suggested for such protection against cognitive dysfunction include effects on atherosclerosis, coagulation, inflammation, as well as direct neuroprotective effects.

Critique 008. Further evidence that moderate alcohol consumption may play a role in the prevention of Alzheimer’s Disease. 13 June 2010

In a case-control study from Spain on the effects of smoking and alcohol use on the risk of Alzheimer’s Disease (AD), the authors found that the risk of AD was unaffected by any measure of tobacco consumption. On the other hand, alcohol consumers showed a 47% lower risk of developing AD than did never consumers, with effects mainly among women and among never smokers. No differences were noted by type of alcoholic beverage consumed. The authors conclude that mean daily total consumption of alcohol showed increasingly protective dose-response relationships in women.

The numbers in this analysis were rather small, and there is always the possibility of confounding by other lifestyle factors. Still, the study supports a number of previous epidemiologic studies showing a lower risk of developing AD for moderate consumers of alcohol.